| AA Battery |
The most common size battery; comes in disposable and rechargeable
types. |
|
| A/D Converter |
Analogue to Digital Converter; the device that converts analogue data
(e.g. a picture) into the required digital signal. |
|
| AA Filter |
Anti-Aliasing Filter; used in front of camera's image to reduce moire
effects. |
|
| AC Adaptor |
Converts AC Mains power to low-voltage DC for camera; very useful for
prolonged indoor photography. The writer considers it a "must" for
any digicam. |
|
| AE - Aperture Priority |
User selects aperture, camera selects shutter speed according to lighting.
Very useful for controlling Depth of Field. |
|
| AE - Programmed Auto Exposure |
The camera selects shutter & aperture according to light conditions;
you cannot select them yourself. Suitable for most "average" situations
but limiting to the advanced user. |
|
| AE - Shutter Priority |
User selects shutter speed, camera selects aperture according to lighting.
Very useful for "freezing" motion or creating deliberate blur. |
|
| AE Lock |
Ability to "lock" the exposure of the camera, then point the
camera elsewhere; a somewhat cumbersome and limited-use "poor man's
exposure override". |
|
| AF |
Auto focus; the almost universal system whereby the camera detects the
subject distance and focuses the lens. Not all AF systems are equal! Some
are much faster and/or more accurate than others; some perform well in
low light, some don't. The writer prefers cameras with genuine mechanical,
manual focus option. |
|
| Algorithm |
Maths routines used in cameras, often in their colour management and
image compression systems. |
|
| Anti-Aliasing |
A system used to reduce the "stair step" effect sometimes seen
in sharp edges. |
|
| Aperture |
The opening formed by the diaphragm in the lens; in combination with
shutter speed, controls overall exposure. |
|
| Archive |
Secure, long-term storage of anything; in digital photography it naturally
refers to image files. |
|
| Artifact |
Incorrect data on an image file; often shows up as colour fringes, lines
etc.. |
|
| Aspect Ratio |
The ratio of horizontal to vertical dimensions of an image. Example:
The A/R of many digicams is 4:3, whilst the A/R of standard 6" x 4" photo
paper is 3:2, which explains why you can't print the whole image without
cropping part if it or having "waste" paper at the ends. |
|
| Auxiliary Lens |
Better digicams can accept wide-angle or telephoto add-on lenses via
filter thread or adaptors. Very useful for the serious photographer. |
|
| AVI |
A movie in Windows AVI format. Many digicams have the ability to capture
movies, albeit with limited quality. |
|
| AWB |
Automatic White Balance compensates for different colour light sources,
e.g. daylight, tungsten light, fluorescent light etc.. |
|
| B & W |
Universal abbreviation for Black and White. |
|
| Backlight |
Illumination for a LCD screen on a camera. |
|
| Backlit |
Subject mainly illuminated from behind; often causes problems with exposure
unless compensation is used. |
|
| Banding |
The unpleasant effect of graduated colours breaking into large sections
of a single colour. |
|
| Barrel Distortion |
Lens distortion causing straight lines to "barrel" out; the
opposite effect is Pincushion Distortion. Fairly common to some extent
in cheaper lenses (and some expensive ones). |
|
| Bit |
Binary Digit; the 0s and 1s on which all digital information is based. |
|
| Bit Depth |
|
|
| Bitmap |
The method of mapping the pixels that make up an image. |
|
| Bleed |
Printing to the edge of a print without leaving an un printed area. |
|
| Blooming |
In the digital world it refers to the effect seen in an image when a
CCD is overexposed to light; can distort colour and subject. |
|
| Blue Tooth |
VHF radio connection between devices such as cameras, computers, PDAs
etc.; range usually less than 10m. |
|
| BMP |
BitMapped image file format. |
|
| Bracketing |
A series (typically 3-5) of photos taken at specific amounts over or
under the "correct" exposure, to ensure getting at least one "right".
Can be expensive with film, nil cost in digital. |
|
| Brightness |
Lightness value of a pixel from black (0) to white (255). |
|
| Buffer |
Temporary memory storage. A digicam without adequate (or any) buffer
will force you to wait until the image is written to the memory card before
you can take another shot. |
|
| Burst Mode |
Cameras with large buffer memories can take shots continuously to the
buffer capacity, hence a "burst" of pictures. |
|
| Byte |
Eight Bits = One Byte (and one thousand bytes = one kilobyte etc.) |
|
| Calibration |
Adjusting a device to a known standard or matching two or more devices
to each other, e.g. a camera's exposure meter must be adjusted to a known
ISO standard, but a computer and a printer may be adjusted to each other
for colour matching. |
|
| Card Reader |
A device into which is placed the memory card of a camera to extract
the stored data. Card readers may be stand-alone accessories, or may be
incorporated into some devices such as inkjet printers for direct printing
without a computer. |
|
| CCD |
Charge Coupled Device. The "film" of a digital camera. Light
falling on the CCD is ultimately converted into the zeros and ones which
make a digital image. There is a HUGE amount of technology between the
CCD and that picture in your hand! |
|
| CD |
Compact Disc. Read Only storage. |
|
| CDR |
Compact Disc Recordable. Read, Write Once Only (i.e. cannot be erased
and re-written). |
|
| CD-RW |
Compact Disc - Re-Writeable. Can be erased and re-written many times.
Haven't proved as popular as makers may have liked as CDRs are so cheap. |
|
| Centre-Weighted |
A camera exposure metering system which "reads" an area around
the centre of the image. |
|
| CF |
Compact Flash Card. A memory storage card of the Compact Flash standard.
CF Type I is a 5mm high solid state card, while CF Type II is a 9mm high
solid state or Microdrive card. |
|
| Chroma |
The value of saturation + hue of a pixel; its colour. |
|
| Chromatic Aberration |
In digital imaging most often seen as unwanted purplish lines along edges
separating dark and light areas. |
|
| CIFF |
Camera Image File Format; picture file storage format used in many cameras. |
|
| CMOS |
Complementary Metal Oxide Semiconductor. An imager device similar to
a CCD but with lower power consumption. |
|
| CMS |
Colour Management System. Software and/or hardware system to calibrate/match
the inputs/outputs of devices in the imaging production chain, e.g. monitors,
computers, printers etc.. Whilst very acceptable results may be obtained
from today's consumer digital products, the precise colour management required
in the pro field is a science in itself. |
|
| CMYK |
Cyan Magenta Yellow Black (why "K" for black? Probably because "B" was
already used for Blue in RGB). Colours displayed on TVs, monitors etc.
use RGB (Red Green Blue), whilst colours on printed paper such as magazines
are created using CMYK. Converting RGB to CMYK can be a big headache, which
is why we have Colour Management Systems. |
|
| Colour Balance |
A measure of how accurately the colours in a digital image match the
original. |
|
| Colour Cast |
An unwanted amount of one or more colours in an image. |
|
| Colour Space |
Digicams use a known colour profile (i.e. a standard) for their images
so they may be reproduced with greater accuracy; this is the Colour Space.
Two popular ones are sRGB and Adobe RGB (which we use on this site where
possible). Colour Space data is stored in the Exif Header section of a
JPEG image file. |
|
| COM Port |
The standard RS-232 Serial Communications Port on computers. Many digicams
can transfer files via the COM port, but it's painfully slow compared to
the later USB standard. |
|
| Compression |
Digital images can take up lots of storage, so most are compressed in
some way. Compression is usually a trade-off however between file size
and quality. |
|
| Continuous Tone |
An image which which does not display an "jumps" from one colour
brightness level to another, i.e. a smooth transition. |
|
| Contrast |
The difference between different brightness areas. |
|
| CRW |
The raw file format from the CCD in Canon cameras; from "CanonRaW". |
|
| DC |
Direct Current; battery power or power from an AC Mains Adaptor. |
|
| Dedicated Flash |
Flash units made to work only with the same-brand camera (e.g. Nikon
camera, Nikon flash). There is an unfortunate trend in digicam makers to
produce cameras which will only work easily with same-brand flashes, a
trend which I loathe. I believe ALL DECENT digicams should have a standard
connection for external flash units (such as Metz, Sunpak, Bowens etc.)
just as virtually all "old fashioned" film cameras did. Progress
- Ha. |
|
| Depth of Field |
A lens can only focus exactly at ONE distance at one time; everything
behind or ahead of that point will be out of focus to some extent. The
distances to which it's out of focus (and therefore "acceptably sharp")
is the Depth of Field. DOF is affected both by lens aperture and distance
of point of focus. There's a whole article about it on this site under
Tutorials > Sharpness. |
|
| Digital Film |
Term used to describe flash memory cards, probably dreamed up by some
yuppie marketing mob to make "film buffs" more comfortable with "digital".
Ugh. |
|
| Digital Zoom |
A "feature" on most digicams which electronically magnifies
the centre section of the image. The "zoomed" image is less sharp;
I never use this "feature" and I wouldn't pay extra for it on
any camera. |
|
| Dioptre Adjustment |
Varies the optical viewfinder's magnification to suit the user's eyes;
may be very useful to essential if you ware spec's.. Not every camera has
it, so if you ware glasses, try before you buy. |
|
| DPI |
Dots Per Inch. Used to express the resolution of a screen display or
printer output. |
|
| DPOF |
Digital Print Order Format allows printing information such as which & how
many prints to be printed, to be embedded on the memory card along with
the image file. An increasing number of printing devices / services can
use this feature. |
|
| DRAM |
Dynamic Random Access Memory. Volatile memory; when the power's turned
off, it's gone! |
|
| DRAM Buffer |
Digicams must have some DRAM Buffer to process the image prior to writing
to the memory card; the better cameras have more DRAM Buffer. Cameras with
a "burst" mode require a large buffer of 32Mb or more. |
|
| Dynamic Range |
The ration between the brightest and darkest areas of an image that can
be successfully recorded. A typical indoor scene with low contrast will
have low dynamic range; an outdoor scene in bright sunlight with bright
highlights and deep shadows will have high dynamic range. Put very simply,
a digital camera with high dynamic range will reproduce a contrasty scene
more faithfully. |
|
| ERI - JPEG |
Extended Range Imaging Technology is a proprietary file format used by
Kodak in pro cameras. |
|
| EV |
Exposure Value (EV). The amount of light required for a given exposure.
At a given ISO, certain shutter/aperture combinations will produce that
exposure, e.g. at ISO100, an Exposure value of 10 (EV10) may be achieved
using 1/8s @ f11, 1/15s @ f8, 1/30s $ f5.6 and so on. |
|
| EVF |
Electronic View Finder. A small colour LCD screen with a magnifier, taking
the place of the more common optical viewfinder. Does not replace the larger
LCD screen found on the rear of cameras. |
|
| EXIF |
Exchangeable Image File Format refers to the camera, exposure and other
data embedded in the JPEG file (sometimes called "Exif Header Information"). |
|
| Exif Print |
Exif 2.2 is a printer independent standard allowing the recording of
certain camera settings. When "processing" the image file, an
Exif compatible application can use this information for more efficient
image production. |
|
| Exposure Compensation |
The ability to override the camera's meter system by a set amount. Can
be very useful in difficult lighting conditions which may "trick" the
meter. |
|
| File Format |
Pictures may be in a confusing number of file formats; fortunately you
will probably only have to deal with common ones such as JPEG, TIFF, BMP
and PSD if you use Photoshop. |
|
| Fill Flash |
Many photos which don't actually "need" flash to achieve accurate
exposure may still benefit from using it. Filling in unsightly shadows,
softening contrast, adding some "depth" to photos are all uses
of fill flash. Take some time to learn about it. |
|
| FireWire |
High speed data protocol used on some cameras for file transfer. Also
known as IEEE1394 and iLink. |
|
| Firmware |
No hard, not soft, just firm (sorry). The name given to a usually-very-small
bit of software stored in a device's Read Only Memory (ROM. Just about
all digital devices have this "instruction set". One often hears
of a "firmware upgrade" for a camera, meaning a new Instruction
Set mini-program is available to improve performance. |
|
| Fixed Focal Length |
Most digicams come with zoom lenses; those that don't are said to have
a lens of fixed focal length. |
|
| Fixed Focus Lens |
Some cheap cameras have lenses which are fixed at one focal point (they
are focused at one distance and you can't change it). They rely on Depth
Of Field to achieve hopefully-acceptable sharpness. I would avoid these
cameras. |
|
| Flash |
Nearly all digicams have a built-in flash; most of these are low-to-very-low
power and are therefore only useful over a limited range. Many manufacturers
such as Nikon and Canon make a range of add-on flash units of greater power
which are fare more useful. Unfortunately many consumer digicams lack an
easy connection for excellent non-original flashes such as the Metz range.
One of my pet peeves. |
|
| Flash Memory |
The Compact Flash Card, SmartMedia Card, Memory Stick etc. you put in
your camera to record images. As flash memory is non-volatile it does not
lose data when power is switched off. |
|
| Flashpath |
A device which looks like an old floppy disk, into which is inserted
a memory card. The device tricks your computer into thinking it's reading
a floppy disk so you can extract the files on the card. Runs on button
battery power and goes in the floppy drive. |
|
| Focus Assist |
Visible or IR light system used by some cameras to help autofocus accurately
under low light levels. |
|
| f-stop |
A number indicating the size of the diaphragm's aperture in a lens. An
f-stop number is not a constant measurement, but is calculated from the
size of the aperture and the focal length of the lens. On a given lens
an aperture of f2.8 is larger than an aperture of f11. |
|
| Gamma |
Can be a complex subject! In simplest terms high contrast = high gamma
and low contrast = low gamma, but there's a lot more to gamma than this. |
|
| Gamma Correction |
Often refers to the accurate display of an image on a computer screen.
A good image may look very poor on a screen with incorrect gamma adjustment. |
|
| Gamut |
No device can faithfully reproduce the entire range of colours; those
it can reproduce are its colour gamut. An inkjet printer which produces
a good range of bright colours may be said to have a wide gamut. |
|
| GIF |
Graphic Interchange File format is used a lot in web pages for graphics,
but is NOT suitable for photos, as it can reproduce a maximum of 256 colours. |
|
| Gradation |
As the name suggests, the smooth and gradual change from one colour or
shade to another. |
|
| Grey Level |
A pixel can have a value from 0 (black) to 255 (white); the grey level
is the pixel's brightness. |
|
| Grey Scale |
A series of patches ranging from black to white, with evenly spaced shades
of grey between. Kodak and others make "Grey Scale & Colour Patches" available
from camera stores; they can be very useful to the serious photographer. |
|
| Guide Number |
The Guide Number for a flash unit is calculated by the formula:
GN = f-stop x flash to subject distance. Most GNs are taken at ISO100, but
some makes can cheat! Be aware also some flash spec sheets are in Feet, some
in Metres. |
|
| Histogram |
A histogram is a graph of an image, showing brightness along the horizontal
axis and pixel numbers at each brightness level along the vertical. The
histogram display on a camera is a very useful tool, and you are urged
to learn more about it. |
|
| Hot Shoe |
Attachment on a camera allowing a flash to be fitted, "hot" referring
to the electrical connections. |
|
| Hue |
Describes the whole range of colours in the spectrum. |
|
| ICC Profile |
The International Color Consortium describes rules on colour management.
Printers, cameras etc. can have a "profile" which effectively
tells one device how another "sees" colours, making accurate
reproduction from device to device easier. |
|
| Image Sensor |
The device which captures the image in a digital camera (CCD, CMOS, Foveon). |
|
| Image Stabilisation |
A system for minimising camera shake, usually found only in long (and
expensive) lenses. |
|
| Interlaced |
Describes the scanning of a sensor by odd-then-even lines. |
|
| Interpolated |
Software can "look" at an image, and then create an artificially
larger image by adding extra pixels according to a complex algorithm. Scanner
makers in particular have been guilty in the past of printing dubious specs
by saying a scanner is "9600dpi interpolated" when in fact it's
only 600dpi optical. Advice: Ignore "Interpolated" specs.! |
|
| Intervalometer |
A device to trigger a camera at set intervals, i.e. Time Lapse photography. |
|
| IR |
Infra Red; light in the infra-red part of the spectrum. Invisible to
humans, it's used for communication and autofocus systems. |
|
| ISO |
International Standards Organisation. In a digicam it relates to the
sensitivity of the camera's sensor / meter system (ISO100, ISO400 etc.).
Previously known as "ASA". |
|
| JFIF |
Also known as EXIF it is a certain specification of the JPEG file format. |
|
| JPEG / JPG |
Joint Photographic Experts Group is the committee which developed the
widely used JPEG image file format. |
|
| Lag Time |
A problem virtually unheard of with "old" film cameras, lag
time is the bane of many digicam owners. "Lag" is the delay from
the moment you press the shutter button to when the camera captures the
image. |
|
| Landscape Mode |
Holding camera horizontally; vertically = Portrait Mode. |
|
| Macro |
Ability of a lens to focus close enough to reproduce objects at an image
ratio of 1:1. In practice, the term "macro" seems to be used
by any maker to describe any lens which focuses "fairly close" to
a subject. Beware of deceptive advertising! |
|
| Matrix Metering |
Many cameras use a matrix metering method where the meter up to 256 sectors
of the frame to obtain an ultimate exposure. |
|
| Megapixel |
Camera makers use this like horsepower in cars - the more the better,
except it isn't necessarily so. All things being equal, a 3Mp camera will
produce better pics than a 2.5Mp camera, but all things are seldom equal.
Lens quality, software quality and a host of other factors will effect
the result. |
|
| Memory Stick |
Sony's own flash memory card "standard" (standard to Sony,
anyway). |
|
| Microdrive |
IBM's ultra-small hard disc memory device in the form of a Compact Flash
Card II package. |
|
| MMC |
Multi Media Card is identical size and shape to the Secure Digital (SD)
Flash cards; used in some cameras and MP3 players. |
|
| Moire |
Coloured rainbow or checkered pattern. |
|
| MOV |
Apple's QuickTime Movie File format. |
|
| Movie Clip |
Motion captured in MPEG, AVI or MOV format. Many digicams can capture
some movie clips, some with sound. |
|
| MPEG |
Motion JPEG; sequence of JPEG images. |
|
| Multi Area Focusing |
Camera attempts to analyze which area to use for focusing. |
|
| Multi Pattern Metering |
Meter reads many different areas of the frame. |
|
| NEF |
Nikon Electronic Format is the raw image file format used by Nikon's
upper-level cameras. |
|
| NiCd |
Nickel Cadmium battery; now largely replaced by NiMH batteries. |
|
| NiMH |
Nickel-Metal Hydride batteries are rechargeable and are claimed to have
no "memory" effect as do NiCds. |
|
| Noise |
In digicams, random groups of red/green/blue pixels. usually happens
at longer exposure times or shooting at higher ISO settings. |
|
| Noise Reduction |
Some cameras have a noise reduction facility which attempts to reduce
noise effects. |
|
| OLED |
Organic Light Emitting Diode is a display technology which doesn't need
a backlight and has better contrast than a LCD. |
|
| Optical Viewfinder |
Camera viewfinder through which one looks at the scene. Better ones have
a dioptre adjustment for those who wear glasses. |
|
| Optical Zoom |
Means the camera has a genuine zoom lens, not just a "digital zoom" which
the writer considers a bit of a gimmick. |
|
| ORF |
Olympus raw file format used by up-market Olympus cameras. |
|
| Orientation Sensor |
Sensors when the camera is turned vertically or horizontally (some also
do when the swivel LCD is turned) and "flips" the image accordingly.
The writer considers this very useful when taking some "product" photographs. |
|
| Overexposure |
Too much exposure, image too light, highlights and colours washed-out. |
|
| Parallax |
In close-up photography, the optical viewfinder
being offset from the taking lens, does not "see" exactly the
same field of view, often resulting in a subject being partly cut off.
The effect does not happen
when using the LCD screen, cameras with Electronic Viewfinders, nor with
true SLR cameras. |
|
| PC Terminal |
No, not "personal computer", this is a type of electrical connector
to plug an external flash into a camera. PC terminals were virtually universal
on film cameras years ago, and SHOULD be almost universal on GOOD digital
cameras today; sadly, they're not, thereby limiting YOUR creativity with
your expensive digital pride and joy. |
|
| PIM |
Print Image Matching is Epson's standard for information embedded in
the Exif headers of a JPEG image file. |
|
| Pixel |
Picture Element; the smallest piece of a picture. |
|
| Plug 'n' Play |
System supposed to make life super-easy when connecting new devices to
Windows computers. Many users refer to it as "Plug 'n' Pray". |
|
| Polarising Filter |
Can reduce glare similar to polarising sunglasses. Comes in two types
- Linear and Circular; use Circular on digicams as Linear can effect autofocus
systems. |
|
| Progressive Scan |
An image sensor which collects data and processors every scan line in
sequence. |
|
| RAW |
The raw image files from the camera's chip. |
|
| Red-Eye |
The un-natural, red-eyed look when photographed by a camera with the
flash too close to the lens (as is the case with nearly all consumer digicams
and film cameras). Using a flash on the camera hotshoe may help; using
an off-camera flash is even better. Most cameras have a red-eye reduction
flash mode which can help reduce this effect. |
|
| RGB |
Red, Green, Blue - the primary colours. |
|
| RS-232 |
Standard Serial Port on most PC computers. The majority of post-2001
digicams don't have this type of connection any more - it's too slow compared
to USB. |
|
| SD |
Secure Digital card is a flash memory card used in digicams and MP3 players;
designed to hold copyright data such as music. |
|
| Self Timer |
The self timer usually has a delay of between 2-10 sec., and can be used
to allow the photographer to get into the frame. As many digicams don't
have a remote release (like the good old fashioned cable release of film
cameras) it can act as an excellent vibration-free shutter release. |
|
| Shutter |
Most digicams use a mechanical/electronic shutter; some use electronic
only. |
|
| Skylight Filter |
A standard accessory for the film camera, the sky filter's ability to
reduce excess blue in outdoor shots is largely handled by a digicam's white
balance. Can be used to protect lens from dust, fingerprints etc.. Sadly
many consumer digicams don't have filter threads. |
|
| Slow Sync |
Also called Night Scene or Night Portrait, it opens the shutter longer
than normal, then fires the flash, thus lighting the foreground by flash
but also correctly exposing the background. |
|
| SLR |
Single Lens Reflex. Nikon D1x, Sigma SD-9 etc. are SLRs. Lenses are fully
interchangeable, cameras usually have excellent image quality and many
features. |
|
| SmartMedia |
SSFDC Cards are very small, thin, flash memory cards. Whilst not as robust
as larger cards, they are super-small in size. |
|
| TFT |
Thin Film Transistor is a type of LCD screen used in digicams. |
|
| Thumbnail Image |
A small, low resolution version of a larger image, used for quick viewing
and evaluation. |
|
| TIFF |
Tagged Image File Format is a lossless, uncompressed image file format.
A given image in TIFF is usually a much larger file than a JPEG for example,
but a TIFF file can be manipulated in editors like Photoshop without loss
of quality. |
|
| Underexposure |
An underexposed image will be too dark, shadow areas will lose detail. |
|
| Unsharp Masking |
Despite the name it's a process designed to increase visual sharpness.
Many cameras will apply some unsharp masking automatically. Most digital
images will benefit from the application of unsharp masking, however care
must be exercised; too much and the result is awful. |
|
| USB |
Universal Serial Bus is a high-speed I/O port on most modern digicams
and computers. Much faster than the RS-232 port, USB 1.1 can trans at 12Mb/s;
USB 2.2 around 400Mb/s. |
|
| Video Out |
Cameras with a Video Out port can output their images to a compatible
TV or monitor. |
|
| Vignetting |
The darkening of the outer edges of a frame, especially corners. Mostly
seen with lenses at widest-angle setting, or when using an accessory which
cuts into the field of view. |
|
| White Balance |
A camera system which adjusts the colour balance of the image to compensate
for non-white light, e.g. fluorescent light, sunsets etc.. |
|
| X3 Sensor |
The image sensor developed by Foveon as an alternative to traditional
CCD, CMOS sensors. Used in the Sigma SD-9 SLR digital camera. |
|
| xD Picture Card |
Jointly developed by Olympus and Fujifilm, the xD card promises very
high capacity combined with ultra-small size. |
|
| Zoom Lens |
A lens of variable focal length. Most digicams come with some sort of
zoom lens. |
|
